Solomon P S, Shaw A L, Young M D, Leimkuhler S, Hanson G R, Klipp W, McEwan A G
Department of Microbiology and Parasitology, The University of Queensland, Brisbane, Australia.
FEMS Microbiol Lett. 2000 Sep 15;190(2):203-8. doi: 10.1111/j.1574-6968.2000.tb09287.x.
Expression of the dimethylsulfoxide respiratory (dor) operon of Rhodobacter is regulated by oxygen, light intensity and availability of substrate. Since dimethylsulfoxide reductase contains a pterin molybdenum cofactor, the role of molybdate in the regulation of dor operon expression was investigated. In this report we show that the molybdate-responsive transcriptional regulator, MopB, and molybdate are essential for maximal dimethylsulfoxide reductase activity and expression of a dorA::lacZ transcriptional fusion in Rhodobacter capsulatus. In contrast, mop genes are not required for the expression of the periplasmic nitrate reductase or xanthine dehydrogenase in R. capsulatus under conditions of molybdenum sufficiency. This is the first report demonstrating a clear functional difference between the ModE homologues MopB and MopA in this bacterium. The results suggest that MopA is primarily involved in the regulation of nitrogen fixation gene expression in response to molybdate while MopB has a role in nitrogen fixation and dimethylsulfoxide respiration.
红细菌的二甲基亚砜呼吸（dor）操纵子的表达受氧气、光照强度和底物可用性的调节。由于二甲基亚砜还原酶含有蝶呤钼辅因子，因此研究了钼酸盐在dor操纵子表达调控中的作用。在本报告中，我们表明钼酸盐响应转录调节因子MopB和钼酸盐对于红假单胞菌中二甲基亚砜还原酶的最大活性以及dorA::lacZ转录融合体的表达至关重要。相比之下，在钼充足的条件下，红假单胞菌中周质硝酸还原酶或黄嘌呤脱氢酶的表达不需要mop基因。这是第一份证明该细菌中ModE同源物MopB和MopA之间存在明显功能差异的报告。结果表明，MopA主要参与响应钼酸盐对固氮基因表达的调控，而MopB在固氮和二甲基亚砜呼吸中起作用。
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